/// <summary>
/// Finds and returns a identity user that matches the userId">.
/// </summary>
/// <param name="userId">The user ID to search for.</param>
/// <returns>An asynchronous Task returns the user if it exists, otherwise returns null.</returns>
public virtual Task <TUser> FindByIdAsync(Guid userId)
{
return(UserSet.FindAsync(new object[] { userId }));
}
